linux/arch/um/kernel
Paolo 'Blaisorblade' Giarrusso cbc24afa82 [PATCH] uml: remove bogus WARN_ON, triggerable harmlessly on a page fault race
The below warning was added in place of pte_mkyoung(); if (is_write)
pte_mkdirty();

In fact, if the PTE is not marked young/dirty, our dirty/accessed bit
emulation would cause the TLB permission not to be changed, and so we'd loop,
and given we don't support preemption yet, we'd busy-hang here.

However, I've seen this warning trigger without crashes during a loop of
concurrent kernel builds, at random times (i.e. like a race condition), and I
realized that two concurrent faults on the same page, one on read and one on
write, can trigger it. The read fault gets serviced and the PTE gets marked
writable but clean (it's possible on a shared-writable mapping), while the
generic code sees the PTE was already installed and returns without action. In
this case, we'll see another fault and service it normally.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13 18:14:14 -08:00
..
skas [PATCH] uml: maintain own LDT entries 2005-11-07 07:53:31 -08:00
tt [PATCH] uml: separate libc-dependent uaccess code 2005-11-07 07:53:31 -08:00
asm-offsets.c kbuild: um fix so it compile with generic asm-offsets.h support 2005-09-09 23:10:54 +02:00
config.c.in Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dyn.lds.S [PATCH] i386 / uml: add dwarf sections to static link script 2005-09-10 12:00:17 -07:00
exec_kern.c [PATCH] uml: remove 2_5compat.h 2005-05-28 16:46:11 -07:00
exitcode.c [PATCH] uml: Clean up prink calls 2005-07-28 21:46:05 -07:00
gmon_syms.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
gprof_syms.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
init_task.c [PATCH] uml: move libc code out of mem_user.c and tempfile.c 2005-09-17 11:50:00 -07:00
initrd.c [PATCH] uml: initrd cleanup 2005-05-20 15:48:18 -07:00
irq_user.c [PATCH] uml: add and use generic hw_controller_type->release 2005-06-21 19:07:32 -07:00
irq.c [PATCH] useless linux/irq.h includes (arch/um) 2005-09-30 08:42:24 -07:00
ksyms.c [PATCH] uml: separate libc-dependent helper code 2005-11-07 07:53:31 -08:00
Makefile [PATCH] uml: separate libc-dependent helper code 2005-11-07 07:53:31 -08:00
mem.c [PATCH] uml: fix hardcoded ZONE_* constants in zone setup 2005-11-07 07:53:32 -08:00
physmem.c [PATCH] uml: big memory fixes 2005-11-07 07:53:31 -08:00
process_kern.c [PATCH] mm: uml pte atomicity 2005-10-29 21:40:42 -07:00
ptrace.c [PATCH] consolidate sys_ptrace() 2005-11-07 07:53:42 -08:00
reboot.c [PATCH] Don't export machine_restart, machine_halt, or machine_power_off. 2005-07-26 14:35:42 -07:00
resource.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigio_kern.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigio_user.c [PATCH] kfree cleanup: arch 2005-11-07 07:54:06 -08:00
signal_kern.c [PATCH] convert signal handling of NODEFER to act like other Unix boxes. 2005-08-29 10:03:11 -07:00
signal_user.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
smp.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
syscall_kern.c [PATCH] uml: fork cleanup 2005-06-25 16:24:35 -07:00
syscall.c [PATCH] uml: system call path cleanup 2005-09-05 00:06:23 -07:00
sysrq.c [PATCH] uml: Fix sysrq-r support for skas mode 2005-10-04 13:22:01 -07:00
time_kern.c [PATCH] jiffies_64 cleanup 2005-10-30 17:37:25 -08:00
time.c [PATCH] uml: Proper clone support for skas0 2005-07-07 18:23:44 -07:00
tlb.c [PATCH] uml: fix condition in tlb flush 2005-09-22 22:17:36 -07:00
trap_kern.c [PATCH] uml: remove bogus WARN_ON, triggerable harmlessly on a page fault race 2005-11-13 18:14:14 -08:00
trap_user.c [PATCH] uml: remove debugging code from page fault path 2005-09-05 00:06:19 -07:00
tty_log.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
uaccess.c [PATCH] uml: separate libc-dependent uaccess code 2005-11-07 07:53:31 -08:00
um_arch.c [PATCH] uml: big memory fixes 2005-11-07 07:53:31 -08:00
umid.c [PATCH] strlcat: use for uml umid.c 2005-09-22 22:17:36 -07:00
uml.lds.S [PATCH] i386 / uml: add dwarf sections to static link script 2005-09-10 12:00:17 -07:00
user_util.c [PATCH] uml: separate libc-dependent helper code 2005-11-07 07:53:31 -08:00
vmlinux.lds.S [PATCH] uml: include the linker script rather than symlink it 2005-05-05 16:36:33 -07:00